２ Climatology of Air-Sea Interaction and Atmospheric Convection
over the Kuroshio in the East China Sea
Fernando R. Cada* and Momoki Koga (Department of Physics and Earth Sciences, University of the Ryukyus)

examine the relationship among these parameters in

1. Introduction

the air-sea interaction and atmospheric convection.

The Kuroshio, one of the most energetic
western boundary currents has a large impact on thesurface water characteristics of East China Sea

2. Datasets and Analysis(ECS) - Fig.1) and greatly influences the atmospheric

All the datasets were downloaded throughconditions in this region. Series of studies byinternet (Table 1), extracted and processed for theAMTEX (Air-Mass Transformation Experiment)

purpose of this study area (Fig.1). These parameters

during 1970’s found out that the increased convective

are the sea surface temperature (SST), wind,transfer

air-mass

precipitation and cloudiness derived from different

transformation was related to the Kuroshio. The

satellite observations about recent ten (10) years,

observational data they used were mainly fromalong with the objectively analyzed heat flux datasets

aerological, surface, upper-air and marine stations inprovided by ship observations obtained froma very limited period of time. But now, with theempirical bulk formula. The climatological monthly

recent advance of ocean satellite technology, satellitemean of each datasets is computed by simply

data provide us more opportunities to study air-sea

averaging the original datasets. By using the monthly

interaction and atmospheric convection over themean data, we can analyze more about a typical

Kuroshio.

feature of convective phenomena in the Kuroshioofheatandmoistureforregion in ECS. The data analysis were made using
the view points of convection as illustrated in Fig.2
referring the available datasets used along with theircorresponding platform satellites and data source.
The methodology analysis used are the following :(a)Contour Map Analysis, (b) Space-Time Diagram(Latitude/Longitude-Time plots), (c) Scatterplots andCorrelations, and (d) Time Series Analysis.
Table 1. List of Datasets used in the study

Fig.1. Study area and typical mean path of the Kuroshio. The vertical andhorizontal lines indicate the section line of data analysis, and thepositions marked n, o, p are selected as a reference points for
air-sea interaction comparison.

Internet Address
Remote Sensing System(RSS)
www.remss.com

This paper investigates the effect of thestrong warm ocean current Kuroshio in the air-sea
interaction in the ECS. The main objectives are: (1)To show the climatology of seasonal differences of
convective process utilizing the monthly mean dataof ocean surface and atmospheric parameters; (2) To* PAGASA/DOST, Science Garden Complex, Agham Road,Diliman, Quezon City, 1101, Philippines.

PODAAC,NASA
http://podaac.jpl.nasa.gov
Weather Home, Kochi
University
http://weather.is.kochi-u.ac.jp
National Oceanography Centre,Southampton University
www.noc.soton.ac.uk- 4 -Database (Satellite)@ SST (TRMM)@ Surface Wind(TRMM, QSCAT)@ Atmospheric WaterVapor@ Cloud Liquid water@ Rain Rates (TRMM)@ SST (NOAA)@ Brightness Temperature
IR1, IR2, IR3,VIS (GMS)@ Sea Surface Heat Flux
(Bulk formula estimation
with COADS dataset)*GMS

ATMOSPHERICCONVECTION

the amount cloud liquid water content is shown in

IR1, IR2,IR3, VIS

Figs.8a and 8b. More cloud-covered areas are foundcaused by the enhanced atmospheric convection

Rain Rate*TMI

Cloud Liquid
Water*QSCAT

particularly in winter and spring seasons.
Water Vapor. Speed. Convergence/Divergence
Wind* TMI/NOAA

Heat Flux*NOC

SSTFig. 2. Basic overview of the convection processes in the air-sea interaction
Showing the parameters used and their corresponding satellites
platforms/source.

3. Results and Discussion
The climatology of SST exhibits a strong
temperature gradient of the warm SST of theFig.3. Mean distribution of SST (0C) over the Kuroshio region during SPRING.

Kuroshio front that marked a boundary separatingfrom the warm waters on the northwestern section of
ECS especially during winter and spring (Fig.3). The
SST variability of the Kuroshio gives significant
effect on surface winds. Intensified wind found along
the Kuroshio path in Fig.4 are modified and affectedby the strong temperature gradient in the wide spreadarea in ECS. The convergence of wind also found in
this area where the location of large amount of heat
flux is observed.
The influence of the warm Kuroshio is very
remarkable during winter and early spring, and there
is a great amount of heat loss advected from theocean to the atmosphere. It is interesting to note thatFig.4. Mean distribution of Surface Wind Speed (m/s) over the Kuroshio
region during WINTER.

over the Kuroshio during spring, flux of heat was still
manifested in spite all over the surrounding ocean
waters heat gain were observed as shown in Fig.5.
Figures 6a and 6b show the variation ofcloud liquid water and rain rates over the Kuroshio atpoint o using their monthly mean variation timeseries. Higher amount of cloud liquid watercorresponds with high precipitation found in late
winter until the last month of spring. Cloud liquidwater were almost observed over the Kuroshio inECS as shown in

Figs. 7a and 7b. The percentage

albedo of cloudiness over this region as inferred by
Fig.5. Mean distribution of Sea Surface Net Heat Flux (w/m2) over the Kuroshio
region during SPRING. Positive (negative) heat gain (loss) by the ocean- 5 - surface is indicated by solid (broken) lines.

(a)

(a)

(b)

(b)

Fig.6. Monthly mean variation time series of (a) Cloud Liquid Water (mm)and (b) Rain Rates (mm/hr) over the Kuroshio region at point o.
The red thick line denotes the yearly average for each month
during the whole analyzed period.

Fig.8. Mean distribution of Visible Albedo (%) over the Kuroshio region
during (a) WINTER and (b) SPRING.

4. Concluding Remarks
This study shows the climatology of(a)seasonal variations about the air-sea interaction andatmospheric convection over the Kuroshio in ECS
using mainly various satellite observed datasets. TheKuroshio is almost stationary along the edge of thecontinental shelf of ECS and simple monthly spatial
mean successfully obtained for some component of
convective phenomena related to the Kuroshio.
Though the typical convective time scale of air-sea
interaction over the Kuroshio were several weeks
shorter than one month, the climatological monthly
mean provided us some sort of conditionally sampled(b)featureobservedinthisarea

showing

theconcentration over the Kuroshio. It also gives us theopportunity of better analysis for the general patternand characteristics of a typical air-sea interaction
phenomena observed over this region.
Fig.7. Mean distribution of Cloud Liquid Water (mm) over the Kuroshio
region during (a) WINTER and (b) SPRING.

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